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1、<p>  鎂薄板合金成形的可鍛性和可成形性的加工技術(shù)</p><p><b>  摘要</b></p><p>  金屬成型和金屬成形機(jī)床的新發(fā)展,顯示了鎂薄片具有優(yōu)秀的模鑄性能,如果工藝是在高溫下傳導(dǎo)。對(duì)鎂薄片成型的相應(yīng)的機(jī)械性能的估價(jià),已經(jīng)在各種各樣的溫度和應(yīng)變率的條件下進(jìn)行的單軸向拉力的測(cè)試。鎂合金az31b、az61b的拉深測(cè)試和m1在200-25

2、0溫度范圍之間都有很好可成形性,除溫度之外,已經(jīng)研究出的極限拉延比也影響模鑄的速度。產(chǎn)生的結(jié)果得出有可能由鎂薄片合金混合物代替?zhèn)鹘y(tǒng)的鋁和鋼薄片的結(jié)論。</p><p><b> ?、?引言</b></p><p>  為了減少燃料消耗、一般已經(jīng)有的成就是減少汽車構(gòu)造的重量的,增加重量輕的物資的使用,在這個(gè)條件下、鎂合金具有對(duì)工商企業(yè)集團(tuán)有特殊的使用價(jià)值,因?yàn)樗麄兊拿芏?/p>

3、低,只有1.74 g/cm3。</p><p>  不久的將來鎂合金將成為汽車零件模鑄的主要地材料。 模具鑄件技術(shù)允許放棄制造過程中復(fù)雜的幾何結(jié)構(gòu)。</p><p>  然而,這個(gè)部分的機(jī)械性能經(jīng)常不能滿足機(jī)械性能的必要條件,(例如耐久強(qiáng)度和延性)。一種有希望能替換的材料,毫無疑問是將模鑄 工藝帶進(jìn)簡便化,那部分對(duì)機(jī)械性能和細(xì)粒的微觀結(jié)構(gòu)有利的沒有氣孔的制造技術(shù)。然而、一種廣泛被應(yīng)用的模鑄

4、技術(shù)在鎂合金的成型的工藝中受到了限制,模鑄技術(shù)和適當(dāng)?shù)墓に噮?shù)的不完善而不得不應(yīng)用(2,3)。鎂薄板金屬部件的應(yīng)用對(duì)汽車車身的構(gòu)造提供一個(gè)很大的潛力。通常、汽車的車身完全由板料沖壓和表現(xiàn)大約25%飛行器質(zhì)量組成。所以,鎂薄片替代傳統(tǒng)的材料應(yīng)用,將導(dǎo)致重量減輕的實(shí)質(zhì)。</p><p> ?、叉V薄片的塑料性質(zhì) </p><p>  鎂合金在室溫下顯示出可成形性的極限,這個(gè)六方晶體和孿晶體的傾向

5、是唯一的允許有限的形變。那不同地定向微晶在獨(dú)立基礎(chǔ)滑動(dòng)平面顯示出畸形,導(dǎo)致一個(gè)相互的滑動(dòng)障礙(4、5)。通過應(yīng)用的溫度完善可以對(duì)模鑄品質(zhì)進(jìn)行可觀的改善! 在200 -225溫度范圍里的可成型性的提高具有很好的可觀性(依靠合金成分) 見文獻(xiàn)《6》的研究。在棱形滑動(dòng)面的六方形結(jié)構(gòu)的熱活化性中發(fā)現(xiàn)了這個(gè)效果,見文獻(xiàn)《7》。</p><p>  2.1成型溫度對(duì)流動(dòng)應(yīng)力的影響</p><p>  

6、一種對(duì)鎂薄片畸形性質(zhì)要求的測(cè)定的詳細(xì)研究的金屬的特征值同樣各向異性或流動(dòng)曲線見《8、9》。 因?yàn)樵谶@個(gè)領(lǐng)域里的系統(tǒng)研究表明對(duì)各種各樣的鎂合金的溫度和應(yīng)變率的可塑性的大量的調(diào)查涉及金屬成型和金屬成形機(jī)床的原理的影響不是可利用的(ifum)。圖1; 顯示鎂 金屬az31b在不同溫度的流動(dòng)曲線 、 顯然那應(yīng)力和可能的拉緊力,大量地依靠在那成型溫度上。在2008c以上溫度范圍內(nèi)流動(dòng)應(yīng)力的減少隨溫度的變化而的

7、變化。</p><p><b>  3 鎂合金的拉深</b></p><p>  為了要研究鎂薄片在不同的成型溫度的可模鍛性,在IFUM與圓筒形工具系統(tǒng)中進(jìn)行拉深測(cè)試,圖3顯示在50c的溫度的拉深測(cè)試的結(jié)果。然而那az31b在低點(diǎn)b01:45可能的拉深比率(拉深:30mm)合金az61b和m1顯示早的破裂,使用b01:6的拉深比率,AZ31 B 顯示與 AZ61 B

8、 和 M 1 類似的 破裂,這些測(cè)試確定鎂合金的可模鍛的低點(diǎn)溫度。 </p><p>  然而,調(diào)查結(jié)果顯示鎂合金在高溫的情況下有非常好的模鍛性。發(fā)現(xiàn)在2008c溫度下az31b的成型溫度具有最大bo的拉深比率,az61b和m1顯示鋁合金b0的最大價(jià)值提高到2:20:2.25.,AlMg4.5 Mn0.4 的比較顯示鋁合金在室溫下非常容易模鍛,鎂合金的增加的拉深比率在低點(diǎn)溫度與提高溫度的比較,結(jié)果表明從可拉長的測(cè)

9、試顯示那應(yīng)力比率在鎂合金的機(jī)械道具的重要的影響力 。</p><p><b>  參考文獻(xiàn)。</b></p><p>  [1] H. Kehler et al., Partikelversta¨rkte Leichtmetalle, Metall Band, 49,Heft 3, 1995.</p><p>  [2] E. Doe

10、ge, K. Dro¨der, St. Janssen, Leichtbau mit Magnesiumknetlegierungen— Blechumformung und Pra¨zisionsschmieden TechnischerMg-Legierungen, Werkstattstechnik, Band 88, Heft 11/12,1998.</p><p>  [3] E.

11、Doege, K. Dro¨der, F.P. Hamm, Sheet Metal Forming ofMagnesium Alloys, Proceedings of the IMA-Conference on MagnesiumMetallurgy, Clermont-Ferrand, France, October 1996.</p><p>  [4] H.J. Bargel, G. Schul

12、ze, Werkstoffkunde, VDI-Verlag GmbH,Du¨sseldorf, 1988.</p><p>  [5] C.S. Roberts, Magnesium and Its Alloys, Wiley, New York, 1960.</p><p>  [6] G. Siebel, in: Beck (Ed.), Technology of Magn

13、esium and Its Alloys,Hughes, London, 1940.</p><p>  [7] N.N.: Magnesium and Magnesium Alloys, Ullmann’s Encyclopediaof Industrial Chemistry, Reprint of Articles from 5th Edition, VCH,Weinheim, 1990.</p>

14、;<p>  [8] E. Doege, K. Dro¨der, Processing of magnesium sheet metals by deepdrawing and stretch forming, Mat. Tech. 7–8 (1997) 19–23.</p><p>  [9] E. Doege, K. Dro¨der, St. Janssen, Umforme

15、n von Magnesiumwerkstoffen,DGM-Fortbildungsseminar, Clausthal-Zellerfeld, Oktober1998, pp. 28–30.</p><p>  [10] L. Taylor, H.E. Boyer, in: E.A. Durand, et al. (Eds.), MetalsHandbook, 8th Edition, Vol. 4, Ame

16、rican Society of Metals,</p><p>  Cleveland, OH, 1969.</p><p>  Sheet metal forming of magnesium wrought magnesium wrought alloys— formabilityand process technology</p><p><b>

17、  Abstract</b></p><p>  New developments at the for Metal Forming and Metal Forming Machine Tools show that magnesium sheets possess excellent forming behavior, if the process is conducted at elevated

18、 temperatures. For the evaluation of mechanical properties relevant for forming of magnesium sheets, uni axial tensile tests have been carried out at various temperatures and strain rates.</p><p>  Deep draw

19、ing tests with magnesium alloys AZ31B, AZ61B, and M1 show very good formability in a temperature range between 200 and</p><p>  2508C. Besides temperature, the influence of forming speed on limit drawing rat

20、io has been investigated. The obtained results lead to the conclusion that it is possible to substitute conventional aluminum and steel sheets by using magnesium sheet metal wrought alloys.</p><p>  1. Intro

21、duction</p><p>  In order to reduce fuel consumption, general efforts have been made to decrease the weight of automobile constructions by an increased use of lightweight materials. In this framework, magnes

22、ium alloys are of special interest because of their low density of 1.74 g/cm3.</p><p>  Presently, magnesium alloys for the use as automobile parts are mainly processed by die casting. The die casting techno

23、logy allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductili

24、ty). A promising alternative has to be seen in components that are manufactured by forming processes. The parts manufactured by this technology are characterized</p><p>  Automotive body constructions offer

25、a great potential for the application of magnesium sheet metal components.</p><p>  In general, the automotive body completely consists of sheet metal parts and represents a share of about 25% of the entire

26、vehicle mass. Therefore, the substitution of conventional sheet materials by magnesium sheets would lead to essential weight savings in this application.</p><p>  2. Plastic material properties of magnesium

27、sheets</p><p>  Magnesium alloys show a limited formability at room temperature. This results from the fact that the hexagonal crystal structure and the low tendency to twinning only allow limited deformatio

28、ns. The differently orientated crystallites only show a deformation on the individual base slip plane, which leads to a mutual slip hindrance [4, 5]. A considerable improvement of the forming qualities can be achieved by

29、 applying temperature. The considerable increase in formability that occurs in the temper</p><p>  2.1. Influence of forming temperature on flow stress</p><p>  A detailed evaluation of the defo

30、rmation properties of magnesium sheets requires the determination of the material’s characteristic values like anisotropy or flow curves [8, 9]. </p><p>  Because systematic investigations in this area are n

31、ot available, extensive investigations concerning the influence of temperature and strain rate on plastic properties of various magnesium alloys were performed at Institute for Metal Forming and Metal Forming Machine Too

32、ls (IFUM). Fig. 1 displays flow curves of magnesium sheet material AZ31B at different temperatures, determined in the uniaxial tensile test according to EN 10002, part 5.</p><p>  It is obvious that the stre

33、sses and possible strains largely depend on the forming temperature. The decrease of flow stresses in the temperature range above 2008C attributes to temperature-dependent relaxation.</p><p>  3. Deep drawin

34、g of magnesium alloys</p><p>  In order to investigate the formability of magnesium sheets, deep drawing tests at different forming temperatures were carried out at IFUM with a cylindrical tool system.Fig. 3

35、 shows the results of deep drawing tests at a temperature of 50C. Whereas the deep drawing of the alloy AZ31B using a low drawing ratio of b0 1:45 was possible (drawing depth: 30 mm), the alloys AZ61B and M1 showed early

36、 fracture. Using drawing ratio of b0 1:6, AZ31B showed fracture similar to AZ61B and M1. These tests con</p><p>  However, the investigated magnesium alloys show very good formability at higher temperature ,

37、The maximum limit drawing ratio of b0 ; max 2:52 was detected for AZ31B at a forming temperature of 2008C. AZ61B and M1 show maximum values of approximately b0 ; max 2:20 up to</p><p>  2.25. The values of

38、the aluminum alloy AlMg4.5Mn0.4 are displayed for comparison. Due to the good formability of the aluminum alloy at room temperature, the increase in limit drawing ratio with rising temperature is low compared to the magn

39、esium alloys.The results gained from the tensile tests showed the significant influence of strain rate on the mechanical properties of magnesium alloys. </p><p>  [1] H. Kehler et al., Partikelversta¨rk

40、te Leichtmetalle, Metall Band, 49,</p><p>  Heft 3, 1995.</p><p>  [2] E. Doege, K. Dro¨der, St. Janssen, Leichtbau mit Magnesiumknetlegierungen</p><p>  — Blechumformung und P

41、ra¨zisionsschmieden Technischer</p><p>  Mg-Legierungen, Werkstattstechnik, Band 88, Heft 11/12,</p><p><b>  1998.</b></p><p>  [3] E. Doege, K. Dro¨der, F.P.

42、Hamm, Sheet Metal Forming of</p><p>  Magnesium Alloys, Proceedings of the IMA-Conference on Magnesium</p><p>  Metallurgy, Clermont-Ferrand, France, October 1996.</p><p>  [4] H.J.

43、 Bargel, G. Schulze, Werkstoffkunde, VDI-Verlag GmbH,</p><p>  Du¨sseldorf, 1988.</p><p>  [5] C.S. Roberts, Magnesium and Its Alloys, Wiley, New York, 1960.</p><p>  [6] G. Si

44、ebel, in: Beck (Ed.), Technology of Magnesium and Its Alloys,</p><p>  Hughes, London, 1940.</p><p>  [7] N.N.: Magnesium and Magnesium Alloys, Ullmann’s Encyclopedia</p><p>  of In

45、dustrial Chemistry, Reprint of Articles from 5th Edition, VCH,</p><p>  Weinheim, 1990.</p><p>  [8] E. Doege, K. Dro¨der, Processing of magnesium sheet metals by deep</p><p> 

46、 drawing and stretch forming, Mat. Tech. 7–8 (1997) 19–23.</p><p>  [9] E. Doege, K. Dro¨der, St. Janssen, Umformen von Magnesiumwerkstoffen,</p><p>  DGM-Fortbildungsseminar, Clausthal-Zel

47、lerfeld, Oktober</p><p>  1998, pp. 28–30.</p><p>  [10] L. Taylor, H.E. Boyer, in: E.A. Durand, et al. (Eds.), Metals</p><p>  Handbook, 8th Edition, Vol. 4, American Society of Me

48、tals,</p><p>  ol. 4, American Society of Metals,</p><p>  Cleveland, OH, 1969.</p><p>  [11] K. Siegert, et al., Superplastische Aluminiumbleche — Verarbeitung</p><p>

49、  mit numerischen Pressen, Metall, 45 Jahrgang, Heft 4, 1991.</p><p>  [12] E.F. Emley, Principles of Magnesium Technology, Pergamon Press,</p><p>  Oxford, 1966.</p><p>  [13] D. S

50、chmoeckel, Temperaturgefu¨hrte Prozeßsteuerung beim Umformen</p><p>  von Aluminiumblechen, EFB-Forschungsbericht, Nr. 55, 1994.</p><p>  [14] H. Beißwa¨nger, Warmziehen von

51、Leichtmetallblechen, Mitteilung</p><p>  der Forschungsgesellschaft Blechverarbeitung, Nr. 27, 1950.</p><p>  [15] E. Kursetz, Die Anwendung von Wa¨rme bei der Herstellung von</p>&l

52、t;p>  Blechformteilen aus Schwer Umformbaren Werkstoffen, Ba¨nder</p><p>  Bleche Rohre, Nr. 5, 1974.</p><p>  [16] O. Heuel, Optimierung der Werkzeugtemperatur Durch Richtige</p>

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